docs: async def call(proxy, method_name, signature, args, flags=0, timeout_msec=-1):
      """
      Asynchronously call the specified method on a DBus proxy object.
  
      :param Gio.DBusProxy proxy:
      :param str method_name:
      :param str signature:
      :param tuple args:
      :param int flags:
      :param int timeout_msec:
      """
      future = Future()
      cancellable = None
      proxy.call(
          method_name,
          GLib.Variant(signature, tuple(args)),
          flags,
          timeout_msec,
          cancellable,
          gio_callback,
          future,
      )
      result = await future
      value = proxy.call_finish(result)
      return pack(*unpack_variant(value))